Thousands of people have signed an online petition to protest against the deportation of a popular London shop worker detained by immigration officers the day after article 50 was triggered who has lived in the UK for 26 years.

Stojan Jankovic, 53, known as “Stoly”, who fled former Yugoslavia in 1991, was detained without warning on Thursday and told he could be deported as early as Tuesday.

A #savestoly campaign on Twitter has attracted huge support, including from Match of the Day presenter Gary Lineker. A petition on the 38 Degrees websitehad been signed by almost 9,000 within 24 hours as Jankovic’s MP, Keir Starmer, wrote to the home secretary, Amber Rudd, to call for the deportation to be delayed by at least 14 days to allow time for a legal challenge.

Jankovic has worked at the Earth Natural Foods shop in Kentish Town Road for 15 years, paying national insurance and tax, according to his employer, John Grayson.

For the past 10 years, he has signed on every month at an immigration reporting centre in London Bridge, Grayson told the Guardian. “Last Thursday afternoon, he went down there, and instead of signing a piece of paper, they locked him up and put him in a van, with no warning at all, so he only had the clothes he stood up in,” he said.

“It is a horrible shock. He is a very integral member of the community in Kentish Town, very popular, and very well-liked. It has made a lot of people very, very angry that this could happen so arbitrarily,” he said.

“I see myself as completely assimilated. I don’t know what more I can do in that respect. This is my neighbourhood, my culture,” he told the Camden New Journal, which first highlighted his case.

He blamed his situation on his failure to properly understand and deal with Home Office bureaucracy. “I ended up in this mess because I couldn’t fill out my indefinite leave to remain form properly,” he said. It is understood he applied for asylum when he arrived in the UK and was refused, and that his leave to remain expired in 1999, but he has since been working and paying taxes without problem.

He faces deportation to Serbia, which was formed after he left with the breakup of former Yugoslavia. He has no Serbian passport, and said he has “absolutely no frame of reference” with Serbia after such a long absence, and would be dependant on his elderly mother there.

Grayson said: “He has been employed transparently, and openly and honestly. He was given a national insurance number, and when he started working for us he was allowed to work. He had permission to work.” He added: “It hasn’t been underhand or hidden in any way.”

He added a lot of people were linking his detention with article 50. “People can draw their own conclusions,” Grayson said of the timing.